This chapter outlines the approach to the evaluation of climate change, environment, and natural resource management in the context of the Consultative Group of International Agricultural Research (CGIAR), an important network of research institutes aimed to reduce global poverty and hunger, to improve human health and nutrition, and to enhance ecosystem resilience and the environment through international agricultural research and partnership. Evaluating the impact of research activities poses specific challenges that differ from evaluating development programmes or normative work. Given the nature of the work of the CGIAR system, it is important to take a systematic and common approach to evaluation that covers the network’s various dimensions – including its environmental, social, and economic dimensions. Over the last decade the relative importance, the urgency, and share of CGIAR investments in climate change research in relation to agriculture has also grown dramatically, together with the gearing up of the CGIAR Research Program (CRP) on Climate Change, Agriculture and Food Security (CCAFS) since 2011, and the evaluation of the CCAFS by the CGIAR-IEA (2016), which forms the basis of the discussion of climate change research and evaluation over the last decade, as well as in this chapter.